linux-kernel - Re: [PATCH -next] kvm/svm: disable KCSAN for svm_vcpu

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Message-Id: <1F15D565-D34D-41F5-B1C5-B9A04626EE97@lca.pw>
Date:   Fri, 17 Apr 2020 09:21:59 -0400
From:   Qian Cai <cai@....pw>
To:     "paul E. McKenney" <paulmck@...nel.org>
Cc:     Elver Marco <elver@...gle.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        kasan-dev <kasan-dev@...glegroups.com>, kvm@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH -next] kvm/svm: disable KCSAN for svm_vcpu_run()



> On Apr 15, 2020, at 11:57 AM, Paolo Bonzini <pbonzini@...hat.com> wrote:
> 
> On 15/04/20 17:37, Qian Cai wrote:
>> For some reasons, running a simple qemu-kvm command with KCSAN will
>> reset AMD hosts. It turns out svm_vcpu_run() could not be instrumented.
>> Disable it for now.
>> 
>> # /usr/libexec/qemu-kvm -name ubuntu-18.04-server-cloudimg -cpu host
>> 	-smp 2 -m 2G -hda ubuntu-18.04-server-cloudimg.qcow2
>> 
>> === console output ===
>> Kernel 5.6.0-next-20200408+ on an x86_64
>> 
>> hp-dl385g10-05 login:
>> 
>> <...host reset...>
>> 
>> HPE ProLiant System BIOS A40 v1.20 (03/09/2018)
>> (C) Copyright 1982-2018 Hewlett Packard Enterprise Development LP
>> Early system initialization, please wait...
>> 
>> Signed-off-by: Qian Cai <cai@....pw>
>> ---
>> arch/x86/kvm/svm/svm.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
>> index 2be5bbae3a40..1fdb300e9337 100644
>> --- a/arch/x86/kvm/svm/svm.c
>> +++ b/arch/x86/kvm/svm/svm.c
>> @@ -3278,7 +3278,7 @@ static void svm_cancel_injection(struct kvm_vcpu *vcpu)
>> 
>> bool __svm_vcpu_run(unsigned long vmcb_pa, unsigned long *regs);
>> 
>> -static void svm_vcpu_run(struct kvm_vcpu *vcpu)
>> +static __no_kcsan void svm_vcpu_run(struct kvm_vcpu *vcpu)
>> {
>> 	struct vcpu_svm *svm = to_svm(vcpu);
>> 
>> 
> 
> I suppose you tested the patch to move cli/sti into the .S file.  Anyway:
> 
> Acked-by: Paolo Bonzini <pbonzini@...hat.com>

Paul, can you pick this up along with other KCSAN fixes?